#include <iostream>
using namespace std;

string s;
int mp[26];
int kind;

int main()
{
    cin >> s;
    int n = s.size();
    int ret = n;
    for(int left = 0, right = 0; right < n; right++)
    {
        if(mp[s[right] - 'a']++ == 0) kind++;
        while(kind == 26)
        {
            ret = min(ret, right - left + 1);
            if(mp[s[left] - 'a']-- == 1) kind++;
            left++;
        }
    }
    cout << ret << endl;
    return 0;
}